Metallurgical furnace roof



Feb. 25, 1958 Filed Sept. 8, 1955 L. B. RlES METALLURGICAL FURNACE ROOF 4 Sheets-Sheet 1 2 FIG. 2.

I Lnis B. Ries MYR/m ATTORNEYS F eb. 25, 1958 L. B. RlEs 2,824,529

METALLURGICAL FURNACE ROOF Filed Sept. 8, 1955 4 Sheets-Sheet 2 FIG. I3. 33 5A* 6m Y l INVENToR.

Lewis B. Ries A TTOR/VE YS Feb. 25, 1958 L. B. RlEs METALLURGICAL FuRNAcE RooF Filed Sept. 8, 1955 4 Shee'ts-She'et 3 FIG. 5.

INVENToR. Y Lewis B. Ries ATTORNEYS Feb. 25, 1958 L. B. RlEs METALLURGICAL FURNACE RooF 4 shets-sheet 4 FiledSept. 8, 195.5

R. m w. m

Lewjgl vB. Ries A T TURA/EVS United States Patent METALLURGICAL FURNACE ROOF Lewis B. Ries, Monessen, Pa. Application september 8, 195s, serial No. 533,116

14 claims.` (121.110-99) This invention relates generally to metallurgical furnaces and is directed particularly to improvements in the roof construction of the same.

lWhile the present invention has been made or developed in connection with furnaces of the open hearth type, it is nevertheless applicable to other types of furnaces wherein the construction embodies an arched roof and also to roofs of the checkerbrick chambers forming a part of the furnace.

Open hearth type furnaces in some constructions have the roof arched from front to back only but sometimes the arching is from end to end also. The refractory bricks used in the construction of the arched roofs are of different chemical composition according to the type of hearth, the roof over the acid hearth being formed of silica brick. The roof is arched across the hearth between the front and back walls of the furnace and rests on skew-back brick set in special skew-back channels secured by rivets or bolts` to the buckstays of the furnace.

While the bricks of the furnace roof are, of course, made to withstand high temperatures, the extremely high temperature to which they are subjected in the operation of the furnace eventually burns them out to an extent where it becomes necessary to shut down the furnace and replace the burned brick. t

Because of the fact that the furnace roof is arched, when the burned bricks are removed, frequently parts lying adjacent thereto which may not require repair or replacement, falls. If a large area of the roof requires repair or renewal, the entire roof may fall, even though the area to be removed may be all on one side of the center of the structure. Thus the requirement for replacement of only a few burned out bricks or the making of a repair on one side of the center of the roof, or adjacent to one end only, may, because of collapse of a larger area, or all, of the roof, result in an extensive repair job. Such an extensive job, therefore, not only is costly because of the great amount of additional labor required but because of the time that the furnace must remain out of service also.

In the light of the foregoing it is a prime object of the present invention to provide a new and novel arched roof construction in which the diiculties at present associated with the making of repairs in the arched roofs of metallurgical furnaces, checker-brick chambers and the like, as above set forth, are eliminated or reduced to a minimum so that less time and labor is involved in making repairs and the length of time that the furnace must be shut down or kept out of service is greatly reduced and accordingly costs incident to the making of the repairs are also materially reduced.

Another object of the invention is to provide, in a manner as hereinafter set forth, an improved arched roof construction, particularly a roof for open hearth and other types of metallurgical furnaces, which is of materially greater strength than conventional furnace roofs.

Another object of the invention is to provide', in a manner as hereinafter set forth, a new and improved arched roof construction for a metallurgical furnace or checker chamber, which is so designed that portions of the roof may be removed for repair without the danger of having large areas of the roof surrounding the part removed for repairs, collapse.

Still another object of the invention is toprovide, in a manner as hereinafter set forth, a new and improved furnace roof construction embodying a full unbroken arch which is divided into a front portion and a b'ack portion and braced or reinforced in such a manner that one portion, or a part thereof, may be removed and rebuilt without disturbing or weakening the other portion and without danger of having the other portion collapse.

A further object of the present invention is to provide, in a manner as hereinafter set forth, a new and improved arched roof construction for an open hearth or other type of metallurgical furnace or for checker chambers, wherein the arch is divided in two portions braced against and separated by a dividing skew-back which is supported independently of the roof portions which it separates so that repairs may be made to one portion or one portion may be removed without disturbing the other portion.

Still another object of the invention is to provide, in a manner as hereinafter set forth, a new and improved arched roof construction for a metallurgical furnace, checker chamber or other structure, which embodies a dividing skew-back structure extending, when in an open hearth furnace roof, from one end of the roof to the other and so designed as to permit longitudinal expansion and contraction under the effects of the furnace heat without damage to the adjoining roof portions.

In the construction of roofs for metallurgical furnaces, particularly furnaces of the open hearth type, use has been made of metal sheathed or metal faced brick. Such bricks have opposite side faces covered by metal plates and when the bricks are set up in the roof structure these metal faced sides are placed in opposing or abutting relation. When the furnace is in operation the abutting or opposing metal plates of the brick become fused together and thus a substantially solid continuous wall results. Accordingly, another object of the invention is to provide a new and improved roof construction having therein a dividing skew-back of refractory material and metal faced on opposite sides whereby metal faced brick may be employed in the roof construction and abutted against the metal faced opposite sides of the skew-back to become bonded by fusion thereto and thus solidly key the skewback in the roof structure.

A still further object of the invention is to provide, in a manner as hereinafter set forth, a novel method of building an arched roof for metallurgical furnaces and the like, having a skew-back incorporated therein in accord ance with the present invention.

The objects set forth are attained, in the construction of a roof for an open hearth furnace, by erectingover the furnace a super structure embodying a number of transverse beams supported at their ends upon the front and back wall buckstays, upon which cross beams is supported a longitudinal girder which Vextends from one end of the furnace to the other.

Secured to the under side of the girder along the length thereof and extending downwardly therefrom are hanger plates which extend across the cross beams and each of these hanger plates is bolted to an upwardly extending| end of a two part post, the lower end of which is embedded in a section of the refractory skew-back. v

The skewback which extends longitudinally of the roof of the furnace is of inverted keystone cross-sectional form and is made up of a number of longitudinal sections having their ends interlocked in such a way as to permit longitudinal expansion and contraction without permitting the escape of products of combustion or heat from the furnace.

Being of inverted keystone cross-sectional form the skew-back has its opposite longitudinal faces upwardly convergent and the brick work of the furnace roof is laid up against these faces and the roof is accordingly divided in two portions each of which spans the space between a side of the central skew-back and the adjacent front or back wall supported skew-back of conventional form.

The roof dividing skew-back is preferably cast or molded in situ by setting up a mold or form of the desired character upon the temporary scaffolding on which the roof bricks are laid up. Suitable reinforcing bars or wires are embedded in the sections of the dividing skew-back by suspending them in the desired positions from the hanging posts upon reinforcing division plates carried by the posts and. by rods extending through the posts longitudinally of the skew-back. After the refractory skewback structure has set, the form therefore may be removed and the roof bricks then set up in the customary manner.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings forming a part of the specification with the understanding, however, that the invention is not confined with a strict conformity with the showing of the drawings but may be changed or modified so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appended claims.

In the drawings:

Fig. l is a view in central longitudinal section through the top part or half of a conventional open hearth furnace.

Fig. 2 is a transverse sectional view taken substantially on the line 2 2 of Fig. 1.

Fig. 3 is a detail section on an enlarged scale showing in transverse section the form for molding the skewback and adjacent parts of the brick work scaffolding and also showing in elevation the supporting means for the skew-back section and reinforcing rods and Wires.

Fig. 4 is a detail section on an enlarged scale taken substantially on the line 4-4 of Fig. 3.

Fig. 5 is a sectional view taken substantially on the line 5-5 of Fig. 3.

Fig. 6 is a detail view on an enlarged scale taken in a .f

vertical plane extending longitudinally of the skew-back and showing one complete section of the skew-back in side elevation, with one hanger arm shown in cross section.

Fig. 7 is a view in perspective of one complete section of the skew-back as it would appear removed from the skew-back structure and showing a portion broken away to show the supporting1 and reinforcing rods and wires.

Fig. 8 is a view corresponding to the lower portion of Fig. 3 showing the form for molding a second embodiment of the skew-back structure wherein the bottom of the skew-back will project beyond the inner face of the furnace roof in the completed roof construction.

Fig. 9 is a sectional view taken substantially on the line 9--9 of Fig. 5.

Fig. l0 is a perspective view illustrating a portion only of the skew-back mold showing the metal side plates in position upon two of the transverse plates for a skewback section upon which the reinforcing rods and wires are mounted.

. Fig. 1l is a transverse section taken substantially on the line 11-11 of Fig. 10.

Fig. 12 is a detail transverse section on an enlarged scale through a side plate of a skew-back section.

Fig. 13 is a view in perspective of one end of a skewback section showing a portion of one metal side plate.

Referring now more particularly to the drawings, Figs. l and 2 illustrate respectively longitudinal and transverse sections through the essential parts of an open hearth furnace and showing in connection with the roof struc` l ture thereof the skew-back construction of the present invention.

.in the illustrated portions of the conventional open hearth furnace the numeral generally designates the hearth while the numeral 12 designates the end walls and the numerals 14 and 16 respectively designate the front and back walls.

The walls are supported or braced at the ends by the upright end buckstays 18 while the sides are supported by the front and back buckstays 20 and 21 respectively. The front buckstays are connected by the horizontal chan nels 22 and similar channels 23 connect the upper ends of the back wall buckstays and these channels are tied together by the transverse tie rods 24. Horizontal channels 25 connect the upper ends of the end buckstays 18 and these are tied together by longitudinal tie rods 26.

The numeral 27 designates the charging doors in the front wall of the furnace while the numeral 28 designates the tapping whole at the back.

The furnace roof, constructed in accordance with the present invention, is generally designated 28 while the longitudinal dividing skew-back of the present invention, incorporated in and forming a part of the roof is generally designated 29. While the skew-back has been separately identified by the reference character 29 it, of course, forms an integral part of the roof structure which is generally designated 28, as will be readily apparent.

In addition to the skew-back forming the central dividing portion of the roof, the roof as thus constructed embodies a front portion 28a and a rear or back portion 281) made or built up in the conventional manner of the required refractory brick. The roof, as is shown in Fig. l is arched longitudinally over the hearth 16 and is also arched transversely throughout its structure as shown in Fig. 2. As is clearly shown in this latter figure the arch s full or complete from the front wall to the back wall and the front and the back edges of the roof sections 28a and 2811 rest along their outer edges upon the conventional side wall supported skew-back brick 30 and 31 which are set in the conventional skew-back channels 32 which are riveted or bolted in the usual manner to the adjacent buckstays.

In referring now and hereinafter to the skew-back and also in the claims, unless it is identified as being the front wall or back wall skew-backs 30 and 31, it will be understood that the reference is to the skew-back structure 29 of the present invention.

The skew-back as shown in Fig. 1, and as hereinbefore stated, extends throughout the length of the furnace from end to end and while it s a continuous structure it is at the same time made up of a plurality of individual sections each of which is designated 33.

The skew-back is cast or molded of any one of the refractories used in the furnace roof or roof brick construction such as quartzite which provides the silica brick in a furnace designed to carry out the acid open hearth process or the skew-back may be made of magnesite and dolomite or conventional magnesite brick material as required in a furnace having the basic hearth.

The skew-back is of inverted keystone cross-sectional form, that is, the cross-section, as shown in Fig. 2, shows side faces which converge slightly toward the top and in the construction shown in Fig. 2 the skew-back is of a vertical thickness approximately the same as the thickness of the roof.

The skew-back is supported in position by a super structure which is generally designated 34 which overlies the furnace roof and is supported upon the front and bach buckstays in the manner about to be described.

The super structure 34 comprises a plurality of transverse beams each of which is generally designated 35 and each comprising two channels 36 disposed in spaced backto-back relation and supported in a suitable manner at their ends upon therupper ends of the front and back buckstays 20 and 21 as shown in Fig. 2.

' The transverse beams 35 support a'single longitudinally extending girder 37 which may be of suitable cross-sectional form but is here illustrated as being in the form of an I beam which is supported at its twoends upon the end buckstays as shown in Fig. l. This girder overlies the skew-back as shown in Fig. 2.

Fig. 7 shows one of the sections of the'skeW-back in perspective with a portion of the same broken away to show elements of the reinforcing structure embedded therein.V Each of these sections is of substantial length and is molded to have the upwardly inclined side faces 38, the flat top face or surface'39 and the wide flat bottom face 46. As previously stated the skew-back in each section is of inverted keystone cross-sectional form so that the side faces converge upwardly. One end face, here designated 41 is formed with a substantially centrally positioned transverse groove 42 while the opposite end face 41a is provided at the same height with the transverse tongue 43 which is adapted to slidably engage in a groove 42 of an adjoining section.

The sections 33 placed end to end with the tongues 43 in adjacent grooves 42 as shown in Fig. l make 'up the complete skew-back and as setup in the roof structure the tongues 43 are spaced slightly from the bottoms of their respective grooves so that a slight longitudinal expansion and contraction can take place in the skew-back, allowance being made particularly for expansion when the furnace is operating. By determination of the amount of expansion which will take place when the furnace is heated it will be apparent that the tongues can be caused to lit tightly in their respective grooves and thus form a tight joint. Such expansion will, of course, be very slight and accordingly will not have any adverse affect upon the adjacent roof sections.

The skew-back is connected with the voverlying transverse beams 35 by a suspension means between eachk section 33 and an overlying beam, in the following manner.

Each section 33 has embedded therein a post which is generally designated 44 and is here illustrated as comprising two T bars 45 arranged with the heads thereof in spaced parallel relation. Each post 44 extends a substantial distance upwardly from the top surface 39 of its section and at its lower end extends through the full height of the section. The head portions of the members 45, which portions are designated 45a are provided in the lower ends thereof where they are-embedded in the section 33, with aligned holes 46 through which extend reinforcing bars 47 which anchor the lower ends of the post members 45 in the section 33.

Each section 33 also has embedded therein a number of transverse plates 48 which are of the same configuration and dimensions as the transverse dimensions and conguration of the section.

The plates 48 each has a number of vertically arranged holes 49 in the central part thereof through which' the bars 47 pass and each plate is provided in the inclined side edges 48a thereof with the inwardly and downwardly directed or sloping slots 50 which maintain, in the assembly of the parts as hereinafter described, in proper horizontal position, the plurality of reinforcing rods or wires 51. Y

Each of the post members 45 has formed through the head portion 45a thereof, two longitudinally directed slots 52 and beneath these slots are apertures 53, the purpose for which is about to be described.

As shown in Fig. 1 each of the sections 33 of-the skew-back has the post 44 thereof disposed directly beneath the space between the two channels of a transverse beam 35.V Welded to the under side of the girder 37 and extending downwardly between the channels 36 of each beam 35 is a xed suspension hanger here shown as a plate 54, the lower end of which extends between the members 45 of an underlying post 44. Each of these hanger plates 54 has therein a pair of slots 55, each of which aligns with two horizontallyV aligned slots 52 to receive a securing bolt 56. As' shown in Fig. 3 the lower ends of the slots 55 overlap the upper ends of the slots 52 and by this arrangement slight vertical movement or adjustment of the skew-back section can occur particularly to take care of any movements due to expansion or upward movement of the underlying structure by reason of the expansion action which may be imparted thereto by the heat of the furnace.

The members 45 of each of the posts 44 have positioned therebetween, between the horizontally aligned slots 53, the lower ends of hanger arms 57 which are secured to the posts by bolts 58 passing through the apertures 53 and through openings in the lower ends of the arms. These arms 57 extend upwardly in divergent relation and have their upper ends, which are provided with the elongate slots 58, positioned between the channels 36 of the adjacent overlying beam 35 and passing through the slots 58 and the channels 36 are retaining bolts 59.

In the construction of the arched roof of the open hearth furnace, there is set up a supporting scaffolding structure upon which the roof bricks are laid the same as in the construction Iof any masonry arch. A portion of such supporting structure is illustrated in Figs. 3, 5, 8 and 10 and generally designated 60. This supporting structure is shown as comprising arch members 61 upon the top of which is placed a suitable covering of sheathing 62. Upon this sheathing the brick work of the roof is placed.

In carrying out the present invention there is set up a mold form which is generally designated 63 and which extends longitudinally of the furnace and comprises the bottom board or wall 64 which rests directly upon and extends across the arch member 61, and the side boards or plates 65 which are secured at their bottom edges to the side edges of the bottom board 64 and extend upwardly at a slight inward slope, in convergent relation as is clearly shown in Fig. 3.

In setting up the parts after the posts 44 are hung in position from the respective suspension plates `54 the group of rods 47 for each section are inserted through the aligned openings or holes 46 after which the plates 48 for each section are put on the rods 47 associated with each post 44.

In Fig. 7 where one of the skew-back sections 33 is shown it will be seen that the section has four of the plates 48 mounted on the rods 47, there being two plates 48 on each side of the post 44.

After the plates 4S have been placed in position the reinforcing wires 51 are inserted in the slots 50.

In Fig. 7 the section 33 is shown as having six reinforcing wires on each side of the post 44 and the group of bars 47 supported thereby. The wires are positioned in pairs which are horizontally spaced or, in other Words, are spaced transversely of the section. This is a preferred construction but it is to be understood that the invention is not limited to the placement of this number of wires on each side of each section 33 or to the specific arrangement shown.

lt will be seen that by sloping the rod receiving slots 50 downwardly and inwardly, after the plates 48 have been positioned the wires or rods 51 can be easily and quickly dropped into position in the slots and will locate themselves automatically in position.

After each post 44 has had the above described rods,

plates and wires hung thereon the side boards or walls` 65 of the form 63 are placed in position and will bear against the inclined edges 48a of the plates 48.

The construction thus far described preparatory to the molding of the skew-back sections will thus form a long trough in which the refractory material for forming the skew-back sections will be placed.

In order to form the skew-back in the sections having the interengaging ytongues and grooves the form is partitignsd, at intervals@ the dirigere shown in Fiss.. 5. and 2.

generally designated 66 which will form the tongue and;

groove ends of the adjacent sections 33. These dividers 66 as shown comprise the upper and lower transverse boards 67 which are positioned in a vertical plane and the connecting horizontally off set central portion 68 which is of substantially U-shaped cross-section and which when filled on the concave side with the refractory material forms the tongue 43 and when covered on the opposite side with the refractory material forms the groove 42 on the adjacent section.

It will, of course, be understood that after the forni 63 has been set up with all of the other parts in place therein and the refractory material has been put into the form and permitted to harden so as to form the skew-back made up of the sections 33 divided by the dividers 66, the side boards 65 of the form will be removed and then the regular refractory brick will be laid against the opposite sides of the skew-back upon the supporting structure 60 in the regular manner to form the two sections 28a and ZSb of the roof construction.

The removal of the side boards 65 will, of course, leave the dividers 66 in place. These dividers remain after the underlying structure 60 is taken away and are permitted to burn out when the furnace is set into operation.

In Fig. 6 which shows a side view of a part of the skew-back the opposing ends of three sections are shown with the tongues and grooves joined and these opposing ends are shown as in spaced relation. This spacing is, of course, closed when the furnace is set in operation as the dimensions are so calculated that the expansion resulting from the heating will produce a tight joint between the ends of the skew-back sections which will prevent escape of products of combustion and l-oss of heat.

The refractory material of which the skew-back is formed will, like the refractories forming the roof sections on each side of the skew-back, eventually be burned away and sections will have to be replaced.

In the construction thus far described the bottom or under side of the skew-back has been shown, as in Fig. 2, in the plane of the under side of the roof sections on each side. However, in order to prolong the life of the skew-back it is contemplated to also construct it of greater vertical thickness than the adjacent sections of the roof so that a portion of the skew-back will project below the adjacent roof portions and Fig. 8 illustrates a way in which the form for the skew-back may be set up so as to make the skew-back in this manner.

In Fig. 8 the brick work supporting scaffolding is generally designated 69a while the arch members are designated 61a and the overlying sheathing is designated 62a.

The arch members 61a may he recessed slightly from the top as indicated at 69 so that the bottom board 64a for the form which is generally designated 63a will be placed below the top of the sheathing 62a and the side boards 65a, of course, extend down int-o the rec-ess 69 to join the bottom board 64a in the manner illustrated.

lt will be readily seen that in this modied construction the plates supporting the reinforcing wires will be of greater height than the plates 48 so as to extend down or the full depth of the form. The plates for this form are here generally designated 48. Since these plates are otherwise the same as the plates 43 and the rods and wires are the same it is not believed that any further detailed description of these parts is necessary to an understanding of themodied construction and it is also believed that it will be readily apparent that when the skewback is fully formed and the ront and back sections of the roof are completed that the lower part of the skewback will form a projecting rib lengthwise of the inner or under side of the furnace roof.

As hereinbefore stated, where the refractory brick for the roof construction may be of the type having metal clad or surfaced side faces the skew-back may be formed with metal covered or clad side faces so that when theA metal clad brick are laid up yagainst the sides of the skewback vthe metal surfaces thereof will become fused or welded to the metal sides of the skew-back when the furnace is set in operation thereby forming a solid bond between the sides of the skew-back and the sides of the adjacent bricks of the front and back roof sections.

Fig. l0 illustrates a portion of the skew-back form with parts of the supporting means and reinforcing means for a section in position therein and showing one method of setting the metal side plates for a section of the skewback in position in the form. In this illustration of the form the same reference characters are employed for those parts which are the same as are illustrated in the preceding figures.

The metal side plates for one section of the skew-back are designated 69. These side plates each comprise an elongate sheet of metal such as steel or the like, designated 70 which is of approximately the same length as the skew-back section to the side of which it is to be joined. The tie bar and tie wire supporting plates 48, two only of which .are shown in Fig. l0, are employed for supporting the metal side plates in position through the utilization of certain of the wire carrying slots 50 in the manner about to be described.

Each plate 70 has a portion of the top edge turned inwardly and downwardly forming the ange 71 which s set at an acute angle to the inner face of the plate while a portion of the lower edge is turned in to form the bottom flange 72 which is disposed at an obtuse angle to the inner face of the plate. As shown in Figs. l0 and ll the the inturned anges 71 and 72 are positioned so that the upper flange 71 can be engaged in an uppermost one of the wire receiving slots of the plates 48 of the skew-back section and the lowermost flange 72 can be slipped into one of the lower slots 50 of the plates 4S. ln this manner, the metal side or face plates will be maintained in position while the side boards of the form are being secured in place.

In addition to having the flanges 71 and 72 by which to mount the plate bodies 70, the bodies are preferably provided with some means whereby they will be firmly bonded to the refractory material of the skew-back section. As an illustration each of the plate bodies may have tongues 73 struck therefrom and pressed inwardly to be embedded in the refractory material of the skewback section whereby to firmly secure the side or face plate to the section. In addition to the tongues 73 being formed to be embedded in the material there will be formed the openings 74 in the metal from which the tongue is pressed, into which some of the material when it is cast in the form, will pass and solidify to firmly bond the plate to the refractory.

It will be seen from the foregoing that by the provision of the skew-back of the present invention in the roof of an open hearth furnace of the type described or in the roof of a checker chamber or other furnace construction the roof will not only be materially strengthened but repairs may be made to a section upon one side of the skewback without the danger of having the section on the other side of the skew-back either fall or be weakened. For example, if a part of the brick work in the front section 28a of the roof has to be taken out for repair the skewback will hold up the opposite section and even portions of the front section adjacent to the removed part will be more rmly supported and will not be so likely to collapse as would be the case in connection with repairing a roof in which the arch is continuous from one side to the other without a central supporting means such as the roofs of the present open hearth furnaces.

As hereinbefore pointed out the provision of the overlapping slots 52 and 55 between the suspension plates and the posts 44 connected therewith not only allows for properly adjusting the parts supported by the post but also allows for any slight tio-and-down movement which may occur due to expansion and contraction of the roof structure.

By the provision of the upwardly and outwardly extending hanger arms any slight lateral movement of the skew-back is effectively prevented. For example, if the whole of one roof section, such as the section 28a, had to be removed the thrust applied to the opposite side of the skew-back by the other section 28b, tending to shift the skew-back laterally would be resisted by the hanger arms 57 on the side of the roof nearest to the section 28b so that such section would be firmly maintained in position while the other section is being replaced.

From the foregoing it will be readily apparent that the present invention constitutes a definite and valuable addition to the art of roof construction for metallurgical furnaces and the like.

I claim:

1. In a metallurgical furnace having front, back and end Walls and buckstays supporting each of said walls; a roof and supporting construction comprising beams supported upon the front and back buckstays, hangers depending from the beams and arranged in a row longitudinally ofthe furnace between the end walls, a skew-back extending lengthwise of the furnace beneath said row of hangers, the skew-back embodying a plurality of elongate sections in end-to-end connected relation, a post secured to and extending up from each of said sections, means securing each post to a hanger, an arcuate front roof section extending from the front wall to and joining one side of the skew-back, and an arcuate back roof section extending from the back wall to and joining the other side of the skew-back, the said roof sections and skew-back forming a single arch between the front and back walls, said supporting construction further including a girder extending lengthwise of the furnace and supported at its ends by the end wall buckstays and between its ends by said beams, and said beams each comprising two juxtaposed channels, said hangers each lying between two channels and secured to the girder and hanger arms coupled to the beams between the channels thereof and attached to the post.

2. A structural unit of the character disclosed comprising an elongate body of formed refractory material, a suspension post embedded at one end in the body and projecting upwardly from the top thereof, metal plates embedded in and disposed transversely of the body upon opposite sides of the post and reinforcing bars in and extending lengthwise of the body and passing through the plates and the post.

3. The invention according to claim 2, wherein said body is of inverted keystone cross sectional form and having a tongue projecting from one end and extending transversely thereof and a groove in and across the other end to receive the tongue of another body.

4. The invention according to claim 2, wherein said plates have slots in opposite side edges and reinforcing wires supported in said slots and extending longitudinally in the body.

5. A structural unit according to claim 2, with a metal facing plate against each of two opposite sides of the body, and means locking the facing plates to the body.

6. A structural unit :according to claim 2, with a metal facing plate against each of two opposite sides of the body, and means coupling the facing plates with the first plates and maintaining the said facing plates against the said sides of' the body.

7. A structural unit according to `claim 2, with a metal facing plate against each of two opposite sides of the body, and means carried by each of the facing plates and engaged in slots in the opposing edges of the embedded 10 metal plates and maintaining the facing plates against the sides of the body. I

8. A structural unit according to claim 2, wherein said metal plates have slots in opposite side edges thereof, a metal facing plate against each of two opposite sides of the body, and inwardly extending flanges along longitudinal edges of the facing plates and engaged in said slots.

9. A structural unit according to claim 2, with a metal facing plate against each of two opposite sides of the body, and elements carried by the facing plates and em bedded in the refractory material and securing the facing plates against the sides of the body.

10. The invention according to claim 9, wherein said elements comprise tongue members projecting inwardly from the facing plates.

l1. The invention according to claim 9. wherein said elements comprise tongue members forming instruck portions of the facing plates.

12. The method of constructing an arched metallurgical furnace roof upon and between two spaced walls which comprises the steps of setting up a supporting super structure, suspending frcm the super structure a plurality of posts in a row occupying a vertical plane lying between said walls, mounting upon the lower end of each of said posts a plurality of reinforcing bars extending longitudinally of said row, mounting a group of metal plates of the same outline and perimetrical dimensions upon said bars of each post to occupy spaced parallel planes extending across said row, attaching reinforcing wires to and between the plates of said groups, constructing lengthwise of said row of plates an elongate form having a bottom and sides enclosing said plates, wires, bars and lower end portions of the posts, filling the form with a refractory of a character to set to a hard condition, removing the form sides after said refractory has set, and then building up an arcuate roof section of refractory brick between each of said walls and a side of the formed hardened refractory material.

13. The invention according to claim 12, with the additional steps of securing combustible separators across the form at spaced intervals before filling the form with the refractory material to mold the material in a number of sections each having a post embedded therein together with a number of plates, rods and wires, and burning out said separators by and in the operation of the furnace.

14. The invention according to claim l2, with the additional steps of securing across the form combustible separators of channeled cross section before filling the form with the refractory material to form a channel across the material on one side of the separator and a tongue on the other side to` lit in the channel and to mold the material in a number of sections each having a post embedded therein together with a number of plates, rods and wires, and effecting the elimination of the separators by burning out the same by and in the operation of the furnace.

References Cited in the file of this patent UNITED STATES PATENTS 325,403 Flagler Sept. 1, 1885 540,805 Walsh June 11, 1895 1,686,386 Loftus Oct. 2, 1928 1,686,387 Loftus Oct. 2, 1928 1,728,265 Farnham et al. Sept. 17, 1929 2,414,255 Dugan Jan. 14, 1947 2,652,793 Heuer et. al Sept. 22, 1953 2,737,912 Kauth et al Mar. 13, 1956 

